Butterfly life cycle stage 3: Pupa

The process from a child to an adult. 

Pupa

 The caterpillar finds a safe place to rest. With a silk thread that comes out of a hole just below its mouth (spinneret), the caterpillar spins a silk pad to attach to. The caterpillar hangs from this pad. Soon, the caterpillar’s skin splits open from head to abdomen, revealing a dull, brownish case underneath—the chrysalis. What is happening in the chrysalis? Inside the chrysalis, the caterpillar is becoming completely liquid and reforming itself into a butterfly. The butterfly pushes from inside until the case splits open, and it slowly struggles out.

When the caterpillar is fully grown, hormones such as prothoracicotropic hormone (PTTH) are produced. At this point the caterpillar stops feeding and begins "wandering" in the quest of a suitable pupation site, often the underside of a leaf.

The caterpillar transforms into a pupa (or chrysalis) by anchoring itself to a substrate and moulting for the last time. The chrysalis is usually incapable of movement, although some species can rapidly move the abdominal segments or produce sounds to scare potential predators.

The pupal transformation into a butterfly through metamorphosis has held great appeal to mankind. To transform from the miniature wings visible on the outside of the pupa into large structures usable for flight, the pupal wings undergo rapid mitosis and absorb a great deal of nutrients. If one wing is surgically removed early on, the other three will grow to a larger size. In the pupa, the wing forms a structure that becomes compressed from top to bottom and pleated from proximal to distal ends as it grows, so that it can rapidly be unfolded to its full adult size. Several boundaries seen in the adult color pattern are marked by changes in the expression of particular transcription factors in the early pupa.